Sapphire monocrystal has a Moh's hardness of 9, which is only lower than diamond. Therefore, a disk diamond saw-blade used to be adopted to cut the sapphire monocrystal for a long time. For a better surface quality, an inner circle-shaped blade and a wire saw plated with the diamond particles are also used for cutting the sapphire monocrystal. The thickness of the disk blade is at least more than 1 mm, causing serious waste of sapphire monocrystal material in processing. However, the fixed-diamond wire saw causes a saw kerf of only 0.2-0.4 mm, reducing the waste of sapphire monocrystal material.
To produce a square crystal block from a sapphire ingot, it is required to use a squaring machine for squaring. The disclosed square machines in the prior art have the following defects.
1. Since the sapphire monocrystal has a high hardness, its cutting efficiency is still low even though the fixed-diamond wire is used for cutting the sapphire monocrystal. In particular, when the cross-section of a workpiece being cut by the fixed-diamond wire is relatively big, the pressure per unit area applied on the workpiece is relatively small and the cutting efficiency is particularly low. Furthermore, the squaring machines disclosed in the prior art have no swing cutter heads.
2. The square machine disclosed in the prior art includes two layers of fixed-diamond wires, which are arranged one above another, intersect with each other, and are apart from one another by a distance of about 50 mm. When the lower layer of fixed-diamond wires come into contact with the workpiece for cutting, the upper layer of fixed-diamond wires are in an idling state. Similarly, after the lower layer of fixed-diamond wires pass through the workpiece, the upper layer of fixed-diamond wires are still cutting the workpiece, while the lower layer of fixed-diamond wires are in the idling state, causing the waste of cutting time.
3. It is not easy to wire the cutter heads and thus the space between the fixed-diamond wires cannot be very small. Generally, the space between the fixed-diamond wires is more than 50 mm, so the sapphire ingot cannot be cut to be a square with a side length of less than 50 mm.